Computer has been starting erratically for awhile. Sometimes it will start., other times it fails and says "HARD DISK NOT FOUND..."

I think the hard drive it finished. With power on I do not feel that 'gyro' effect you normally feel from spinning platters in a good drive.

So I tried a brand new 80GB hard drive. After numerous reboots the BIOS finally recognized it. I was then able to install WinXP. When installation was complete, I did a few Windows updates. Now I'm getting "HARD DISK NOT FOUND..." message again.

Thinking the motherboard battery could be failing, I tried a new one. Made no difference.

I tried new IDE cables. Made no difference.

I set BIOS settings all to default settings. Made no difference. Tried optimized settings. Same thing.